Experiences in the Use of Mini and Modular Roundabouts by Highway Agencies

When: February 6, 2025 | 2:00 - 3:30 PM ET

This webinar is led by the ITE Traffic Engineering Council and ITE Roundabout Committee.

Webinar Description:

While roundabouts continue to be a proven solution for addressing safety and efficiency at intersections in the U.S., the increasing costs of construction and right-of-way have reinvigorated the mini roundabout as a viable option. By definition, a mini roundabout is a type of roundabout in which the central island is fully traversable and intended to be utilized by trucks or other large vehicles. This technique reduces the footprint of the intersection, and mini roundabouts can often be retrofitted within existing intersection footprints. Approximately 300 mini roundabouts have been constructed in the U.S. Like a mini roundabout, a modular roundabout is a specialized roundabout that incorporates prefabricated materials to reduce excavation, paving and drainage, environmental, utility and right-of-way impacts, construction duration, and ultimately, cost. The modular material is typically used for the central island and splitter islands but may also include outside curbing. The material is glued or anchored on top of existing pavement. In addition to these custom-made materials, modular roundabouts employ striping and may include quick-build curbs and flex-posts to delineate vehicle paths. Modular roundabouts are less common in the U.S., but several have been constructed in California, Georgia, North Carolina, Virginia, and Wisconsin.

NCHRP domestic scan 23-01 was conducted during 2024 to describe the experiences and lessons learned of leading states on mini and modular roundabouts. These experiences and lessons learned may be valuable to others who may be considering using mini and modular roundabouts. The scan team met with seven agencies around the US regarding mini roundabouts and four regarding modular roundabouts. The team gathered useful information on capacity and traffic efficiency, crash histories, design and performance checks, construction costs, installation and construction timelines, maintenance, and public/community acceptance. The scan team found overall that mini and modular roundabouts can be viable options at certain sites when the full-sized options are not feasible. This webinar will convey those findings.

Learning Objectives:

• Distinguish mini and modular roundabouts from other types.
• Describe the general status of mini and modular roundabouts around the US in terms of capacity and traffic efficiency, crash history, design, costs, etc.
• Explain generally where a mini and modular roundabout should be considered.

Moderator: 
Christa Greene, Business Development Executive | LJB Engineering | Raleigh, North Carolina, USA

Presenters:

• Joe Hummer, PhD, P.E., NCDOT State Traffic Management Engineer | North Carolina Department of Transportation | Raleigh, North Carolina, USA
• Laura Nesbitt, Highway Engineering Professional | Jacobs | Atlanta, GA, USA
• Joseph Balskus, P.E., PTOE, RSP1, Director of Transportation Systems, VHB, Wethersfield, CT, USA